Organisation Of Cells

Organisation of Cells

• All prokaryotes are unicellular; eukaryotes can be unicellular or multicellular.
• Unicellular organisms include archaea, bacteria, and protozoa; they perform all life processes.
• Colonial organisms consist of individual cells living closely to ensure survival without specialization.
• Multicellular organisms have specialized cells that depend on each other for survival and efficiency.
• Cellular specialization allows diverse functions to be performed simultaneously in multicellular organisms.
• Organelles such as chloroplasts conduct photosynthesis and contain chlorophyll for glucose production.
• Mitochondria perform cellular respiration, generating ATP as the energy currency of the cell.
• Ribosomes, found in rough ER, are responsible for protein synthesis.

Tissues, Organs, and Systems

• Cell differentiation enables specialization for specific functions, triggered by internal or external stimuli.
• Organ: a structure composed of tissues that perform specific functions.
• Tissue types: connective, epithelial, muscle, and nervous.
• Organ system: a group of organs working together to carry out distinct functions.
• Hierarchical organization in multicellular organisms includes cells → tissues → organs → organ systems → organisms.

Size and Surface Area

• As an object increases in size, both surface area and volume grow, but the surface area-to-volume (SA:V) ratio decreases.
• High SA:V ratios facilitate diffusion; low SA:V ratios necessitate specialization to meet metabolic needs.

Nutrient and Gas Requirements

• Autotrophs synthesize their own food from inorganic materials (e.g., plants and algae).
• Heterotrophs obtain energy by consuming other organisms (e.g., animals and fungi).
• Photoautotrophs use sunlight for energy; chemoautotrophs derive energy from inorganic chemical reactions.

Plant Structure and Function

• Leaves are plant organs with layers like mesophyll, rich in chloroplasts for photosynthesis.
• Stomata are pores surrounded by guard cells, regulating water loss during transpiration.
• Stems connect roots and leaves, containing xylem and phloem for nutrient and water transport.
• Xylem transports water upward, while phloem distributes sugars from leaves to other plant parts through the source-to-sink model.

Gas Exchange

• Gas exchange involves oxygen and carbon dioxide; oxygen maintains cellular respiration, while carbon dioxide needs removal to prevent toxicity.
• Alveoli in mammals enable gas exchange; they are thin-walled sacs surrounded by capillaries facilitating diffusion.
• In plants, gas exchange occurs via stomata where carbon dioxide enters for photosynthesis and oxygen exits.

Transpiration and Nutrient Transport

• Transpiration-cohesion-tension theory explains water transport in plants; cohesion keeps water molecules linked as they rise in xylem.
• The structure of phloem (consisting of living tissue with sieve plates and companion cells) allows sugar movement throughout the plant.
• Source-to-sink theory emphasizes the transport of sucrose from production areas to growth areas.

Digestion

• Digestion breaks down food into absorbable nutrients; it involves both physical (chewing, peristalsis) and chemical (enzyme action) processes.
• Nutrients, minerals, and water are absorbed primarily in the small intestine, specifically through the walls of villi.
• The digestive process includes sections of the small intestine: duodenum (chemical digestion), jejunum (nutrient absorption), and ileum (water-soluble vitamin absorption).

Comparisons

• Organisms consist of four biological macromolecules: carbohydrates, lipids, proteins, and nucleic acids, primarily made of CHONPS (carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur).

Transport Systems

• The circulatory system, comprising the heart, blood, arteries, veins, and capillaries, transports oxygen and nutrients and removes waste.
• The heart consists of four chambers: left/right atria and left/right ventricles, facilitating blood circulation.
• Blood serves three primary functions: transport, protection, and regulation of body temperature, with plasma comprising 90% water and 10% other substances.### Blood and its Components
• Plasma is essential in treating burns, shock, trauma, and medical emergencies due to its proteins and antibodies.
• Therapies for rare chronic conditions like hemophilia and autoimmune disorders utilize proteins and antibodies from plasma.
• Red blood cells, produced in red bone marrow, are disk-shaped and transport oxygen and carbon dioxide for 120 days.
• White blood cells (leukocytes) protect against bacteria and viruses; they create antibodies through special proteins that identify foreign materials.
• Platelets are fragments crucial for blood clotting; they adhere to broken cells and secrete clotting factors to form clots.

Blood Vessel Types

• Arteries transport oxygen-rich blood away from the heart; they have thick, elastic walls to withstand high pressure.
• Veins bring oxygen-poor blood back to the heart; they have thinner walls and larger lumens.
• Capillaries are the smallest blood vessels with one-cell-thick walls, vital for nutrient and oxygen delivery as well as waste absorption.

Plant Structure and Vascular Systems

• Autotrophs (plants) possess vascular, root, and shoot systems for structure and transport.
• The vascular system consists of xylem, transporting water and inorganic substances, and phloem, moving organic nutrients like sucrose.
• Root systems anchor plants and efficiently absorb water/minerals, with a branching structure to maximize surface area.
• Stem and shoot systems support leaves for photosynthesis and flowers for reproduction, facilitating fluid transport.
• Leaves contain stomata, controlled by guard cells, which regulate gas exchange and water loss.

Gas Exchange in Plants and Animals

• Investigate how gases move between internal and external environments.
• Closed circulatory systems circulate blood via enclosed vessels; found in vertebrates like fish, amphibians, reptiles, and mammals.
• Open circulatory systems involve pumping hemolymph into a hemocoel surrounding tissues; common in molluscs and arthropods.

Characteristics of Circulatory Systems

• Closed systems deliver fluids directly to cells; open systems allow fluids to bathe organs for diffusion.
• Common functions of both systems include transporting oxygen, nutrients, waste products, and immune cells.

Advantages and Disadvantages of Closed Circulatory Systems

• Advantages: Efficient oxygen delivery, better waste removal, pressure from heart enhances circulation, and an independent lymphatic system.
• Disadvantages: Higher energy requirements and greater system complexity.

Changes in Transport Medium Composition

• During cellular respiration, oxygen and glucose decrease, while carbon dioxide and urea increase in composition as blood passes through various organs:
  • Heart: O2 decreases, glucose decreases, CO2 increases, urea increases.
  • Brain: O2 decreases, glucose decreases, CO2 increases, urea increases.
  • Lungs: O2 increases, glucose decreases, CO2 decreases, urea increases.
  • Kidney: O2 decreases, glucose decreases, CO2 increases, urea increases.
  • Small Intestine: O2 decreases, glucose increases, CO2 increases, urea increases.

Explore the fascinating world of cells with this quiz on cell and organelle structures. Learn about the differences between prokaryotes and eukaryotes, and the significance of unicellular organisms. Delve into the characteristics of archaea, bacteria, and protozoa in this engaging assessment.